Synthesis gas method and apparatus

Abstract

A method and apparatus for producing a synthesis gas product having one or more oxygen transport membrane elements thermally coupled to one or more catalytic reactors such that heat generated from the oxygen transport membrane element supplies endothermic heating requirements for steam methane reforming reactions occurring within the catalytic reactor through radiation and convention heat transfer. A hydrogen containing stream containing no more than 20 percent methane is combusted within the oxygen transport membrane element to produce the heat and a heated combustion product stream. The heated combustion product stream is combined with a reactant stream to form a combined stream that is subjected to the reforming within the catalytic reactor. The apparatus may include modules in which tubular membrane elements surround a central reactor tube.

We claim: 
     
       1. An apparatus for producing a synthesis gas product comprising:
 at least one oxygen transport membrane element having a permeate side and a retentate side, wherein said oxygen transport membrane element is configured to separate oxygen from an oxygen containing stream contacting a retentate side of the at least one oxygen transport membrane element and to combust a hydrogen containing stream, formed of a synthesis gas containing no more than 20 percent methane, at a permeate side of the at least one oxygen transport membrane element in the presence of permeated oxygen thereby to generate heat, a heated reaction product stream and a heated retentate stream; 
 at least one catalytic reactor configured to react hydrocarbons and steam to produce a synthesis gas stream, thereby to at least in part produce a synthesis gas product; 
 the at least one catalytic reactor connected to the at least one oxygen transport membrane element such that the heated reaction product stream is combined with a reactant stream containing hydrocarbons to form a combined stream comprising hydrocarbons contributed by the reactant stream and steam contributed at least by a heated reaction product stream and the combined stream is introduced into the at least one catalytic reactor; and 
 the at least one oxygen transport membrane element and the at least one catalytic reactor positioned with respect to one another and within an elongated insulated housing such that the heat is radiated from the at least one oxygen transport membrane element to the at least one catalytic reactor and is indirectly transferred from the heated retentate stream to the at least one catalytic reactor to assist in supporting endothermic heating requirements of the steam methane reforming reaction. 
 
     
     
       2. The apparatus of  claim 1 , wherein:
 the at least one oxygen separation element is also in flow communication with the at least one catalytic reactor such that the synthesis gas product is formed from a first part of the synthesis gas stream and the hydrogen containing stream is formed from a second part of the synthesis gas stream; and 
 means are provided for cooling the synthesis gas stream and for recycling the second part of the synthesis gas stream to the permeate side of the at least one oxygen transport membrane element. 
 
     
     
       3. The apparatus of  claim 2 , wherein the cooling and recycling means comprises:
 a convective heat exchange network having a series of heat exchangers in flow communication with the at least one catalytic reactor and configured to cool the synthesis gas stream through indirect heat exchange with: the second part of the synthesis gas stream; the reactant stream; a hydrocarbon containing stream containing the hydrocarbons; boiler feed water, thereby to raise superheated steam and a quench steam stream; and cooling water; 
 a flow network associated with the convective heat exchange network to introduce the quench steam stream into the synthesis gas stream prior to the series of heat exchangers, to introduce at least part of the superheated steam into the hydrocarbon containing stream after having been heated, thereby to form the reactant stream and to divide the synthesis gas stream after having indirectly exchanged heat with the hydrocarbon containing stream and the boiler feed water into the first and the second part of the synthesis gas stream; 
 a recycle blower connected to the flow network to recycle the second part of the synthesis gas stream to the permeate side of the at least one oxygen transport membrane; and 
 a knockout drum connected to the convective heat exchange network to remove condensate from the synthesis gas stream after having been cooled, thereby to produce the synthesis gas product. 
 
     
     
       4. The apparatus of  claim 1  or  claim 2  or  claim 3 , wherein:
 a heat exchanger is connected to the oxygen separation device and configured such that the oxygen containing stream is preheated through indirect heat exchange with the heated retentate stream prior to being introduced to the retentate side of the at least one oxygen transport membrane element; 
 the at least one catalytic reactor has a polishing section situated within a duct burner fired by a fuel thereby increasing equilibrium temperature at the outlet of the at least one catalytic reactor and reducing methane slip from the at least one catalytic reactor; and 
 the duct burner is positioned between the oxygen separation device and the heat exchanger such that the heated retentate supports combustion of the fuel within the duct burner prior to preheating the oxygen containing stream within the heat exchanger. 
 
     
     
       5. The apparatus of  claim 1 , wherein:
 the at least one catalytic reactor is at least one first catalytic reactor; 
 at least one second catalytic reactor is configured to react additional hydrocarbons contained in the subsidiary reactant stream with further steam, thereby producing a subsidiary synthesis gas stream; and 
 the permeate side of the at least one oxygen transport membrane element is connected to the at least one second catalytic reactor such that the hydrogen containing stream is formed, at least in part, from the subsidiary synthesis gas stream. 
 
     
     
       6. The apparatus of  claim 5 , wherein the at least one second catalytic reactor is positioned such that the heat generated by the at least one oxygen transport membrane element is also transferred by radiation and through indirect heat transfer from the heated retentate stream to the at least one second catalytic reactor to assist in supporting endothermic heating requirements of the steam methane reforming reaction. 
     
     
       7. The apparatus of  claim 1 , wherein:
 the at least one oxygen transport membrane element is of tubular configuration and the permeate and retentate sides are located on inner and outer surfaces of the at least one oxygen transport membrane element; 
 the elongated, insulated reactor housing has opposed openings situated at opposite ends and houses the at least one oxygen transport membrane element and the at least one catalytic reactor such that the oxygen containing stream is introduced into one of the opposed openings and the heated retentate stream is discharged from the other of the opposed openings; and 
 the at least one catalytic reactor faces the at least one oxygen transport membrane element such that the heat is radiated to the at least one catalytic reactor and the oxygen containing stream contacts the retentate side of the at least one oxygen transport membrane element and thereafter, the heated retentate stream contacts that at least one catalytic reactor to transfer the heat from the heated retentate stream before being discharged from the other of the opposed openings. 
 
     
     
       8. The apparatus of  claim 6 , wherein:
 the at least one oxygen transport membrane element is of tubular configuration and the permeate and retentate sides are located on inner and outer surfaces of the at least one oxygen transport membrane element; and 
 the elongated, insulated reactor houses the at least one oxygen transport membrane element, the at least one first catalytic reactor and the at least one second catalytic reactor and has opposed openings situated at opposite ends such that the oxygen containing stream is introduced into one of the opposed openings and the heated retentate stream is discharged from the other of the opposed openings; and 
 the at least one first catalytic reactor faces the at least one oxygen transport membrane element and the at least one second catalytic reactor is positioned downstream of the at least one first catalytic reactor and facing the at least one oxygen transport membrane element such that the heat is radiated to the at least one catalytic reactor to both the at least one first catalytic reactor and the at least one second catalytic reactor and the oxygen containing stream contacts the retentate side of the at least one oxygen transport membrane element and thereafter, the heated retentate stream contacts that at least one catalytic reactor and the at least one second catalytic reactor to transfer the heat from the heated retentate stream to the at least one second catalytic reactor before being discharged from the other of the opposed openings. 
 
     
     
       9. The apparatus of  claim 7 , wherein:
 the at least one oxygen transport membrane element is formed by a plurality of oxygen transport membrane tubes; 
 the at least one catalytic reactor is formed by reactor tubes containing a catalyst to promote the steam methane reforming reaction and having inlets at one end of each of the reactor tubes and outlets at the other end of the reactor tubes to discharge the synthesis gas stream; 
 the plurality of oxygen transport membrane tubes and the reactor tubes are contained within modules comprising:
 the plurality of oxygen transport membrane tubes positioned so as to surround the central reactor tubes; 
 inlet manifolds connected to the oxygen transport membrane tubes to introduce the hydrogen containing stream into the oxygen transport membrane tubes; 
 outlet manifolds connected to the oxygen transport membrane tubes to receive the heated combustion product stream; and 
 the outlet manifolds connected to the inlets of the central reactor tubes such that the heated combustion product stream is combined with a hydrocarbon containing stream, thereby to form a combined stream to undergo the steam methane reforming reaction; and 
 
 the modules arranged such that a view factor between each of the central reformer tubes and the oxygen transport membrane tubes radiating heat to each of the central reformer tube is greater than or equal to 0.5. 
 
     
     
       10. A reactor module comprising:
 a central reactor tube containing a catalyst to promote a steam methane reforming reaction and having at one end an inlet and at the other end an outlet to discharge a reformed stream; 
 a plurality of oxygen transport membrane tubes surrounding the central reactor tube and configured to separate oxygen from an oxygen containing feed and to generate heat for supporting endothermic heating requirements of the steam methane reforming reaction; 
 an inlet manifold connected to the oxygen transport membrane tubes to introduce a hydrogen containing feed into the oxygen transport membrane tubes for combustion of the hydrogen containing feed supported by oxygen permeating through the oxygen transport membrane tubes and generation of a heated combustion product stream and the heat; 
 an outlet manifold connected to the oxygen transport membrane tubes to receive the heated combustion product stream; 
 the outlet manifold connected to the inlet of the central reactor tube such that the heated combustion product stream is combined with a hydrocarbon containing stream, thereby to form a combined stream to undergo the steam methane reforming reaction; and 
 means for feeding a hydrogen containing stream to the inlet manifold and for feeding a hydrocarbon containing stream to the inlet of the central reactor tube. 
 
     
     
       11. The reactor module of  claim 10 , wherein:
 each of the oxygen transport membrane tubes have an inlet section and an outlet section connected to the inlet section and parallel thereto such that the hydrogen containing stream enters the inlet section and the heated combustion product stream is discharged from the outlet section; and 
 the inlet manifold and the outlet manifold comprises a plate-like element having inlet openings to receive the hydrogen containing stream, a radial arrangement of inlet passages in registry with the inlet openings to feed the hydrogen containing stream into the inlet passages, outlet passages, bores communicating between the inlet sections and the inlet passages to feed the hydrogen containing stream to the inlet sections and communicating between the outlet sections and the outlet passages to feed the heated combustion product stream from the outlet section to the outlet passages and outlet openings communicating between the outlet passages and the inlet of the central reactor tube to feed the heated combustion product stream to the inlet of the central reactor tube. 
 
     
     
       12. The reactor module of  claim 11 , wherein the feeding means comprises an inlet assembly comprising:
 an inlet plenum in communication with the inlet openings; 
 an outer feed tube connected to the inlet plenum to feed the hydrogen containing stream into the inlet plenum and into the inlet openings; and 
 an inner feed tube coaxially positioned within the outer feed tube and extending through the inlet plenum to the inlet of the central reactor tube. 
 
     
     
       13. The reactor module of  claim 12 , wherein the inlet of the central reactor tube is a mixing section positioned between one end of the inner feed tube and the catalyst. 
     
     
       14. The reactor module of  claim 13 , wherein:
 the plate-like element includes a first plate and a second plate connected to the first plate in a juxtaposed relationship; 
 the first plate is connected to the inlet sections and the outlet sections of the oxygen transport membrane tubes and the central reactor tube and has a radial arrangement of grooves to form the inlet passages and the outlet passages, the bores in communication with the inlet passages and the outlet passages and the outlet openings in registry with a portion of the radial arrangement of the grooves forming the outlet openings; 
 the inner feed tube passes through the first plate and the second plate to the inlet of the central reactor tube; 
 the first plate has the inlet openings, the inlet openings positioned so as to be in registry with the a remaining portion of the radial arrangement of the grooves that form the inlet passages; and 
 the inlet plenum is connected to the first plate and encloses the inlet openings.